Activity 2: Coding with Arduino

Week 2 of Building Underwater Robots

Description

In this 30-minute session, students will explore coding with Arduino by building a circuit with 3 single-color LEDs and 1 RGB LED. They’ll learn how to use digital and PWM pins to control light patterns and colors, and write basic Arduino sketches to make lights blink and fade.

Materials Required

• 1 Arduino Uno or equivalent per student
  
• 6 or more male-to-male hookup wires
  
• 3 x 470 ohm resistors (or similar)
  
• 3 LEDs of any color
  
• 1 RGB LED

Presentation Link

Presentation PDF

Learning Outcomes

• Understand the difference between digital and PWM pins on Arduino
  
• Build a circuit using multiple LEDs and resistors
  
• Use digitalWrite() to blink LEDs
  
• Use analogWrite() to control an RGB LED’s color
  
• Debug common wiring/code errors

Agenda

1. Introduction to LED Control

• Review: What is an LED?
  
• Polarity and how to wire an LED safely
  
• Using resistors with LEDs

2. Blinking 3 LEDs

• Connect 3 single-color LEDs to pins 11, 12, and 13
  
• Use digitalWrite() and delay()
  
• Challenge: Create a pattern (e.g., traffic light or chase light)

3. RGB LED Basics

• Common Anode vs. Cathode RGB LEDs
  
• Use PWM pins (9, 10, 11) for red, green, and blue
  
• Create solid colors and mixes using analogWrite()

4. Example Code Snippets

Lesson 1: Blink

/*
  Blink

  Turns an LED on for one second, then off for one second, repeatedly.

  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
  the correct LED pin independent of which board is used.
  If you want to know what pin the on-board LED is connected to on your Arduino
  model, check the Technical Specs of your board at:
  https://www.arduino.cc/en/Main/Products

  modified 8 May 2014
  by Scott Fitzgerald
  modified 2 Sep 2016
  by Arturo Guadalupi
  modified 8 Sep 2016
  by Colby Newman

  This example code is in the public domain.

  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Blink
*/

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(LED_BUILTIN, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);                      // wait for a second
}

Lesson 2: Multiple Blinking Lights

/*
  Blink 3 
*/

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(13, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(13, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);                      // wait for a second
  digitalWrite(12, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(12, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);  
  digitalWrite(11, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(1000);                      // wait for a second
  digitalWrite(11, LOW);   // turn the LED off by making the voltage LOW
  delay(1000);              
}

Lesson 3: RGB LED Mixing

// Source https://learn.adafruit.com/adafruit-arduino-lesson-3-rgb-leds/arduino-sketch

void setup()
{
  pinMode(11, OUTPUT); // Red Pin
  pinMode(10, OUTPUT); // Green Pin
  pinMode(9, OUTPUT);  // Blue Pin
}

void  loop() {
  setColor(255, 0, 0); // Red Color
  delay(1000);
  setColor(0,  255, 0); // Green Color
  delay(1000);
  setColor(0, 0, 255); // Blue Color
  delay(1000);
  setColor(255, 255, 255); // White Color
  delay(1000);
  setColor(170, 0, 255); // Purple Color
  delay(1000);
  setColor(127, 127,  127); // Light Blue
  delay(1000);
}

void setColor(int redValue, int greenValue,  int blueValue) {
  analogWrite(11, redValue);
  analogWrite(10,  greenValue);
  analogWrite(9, blueValue);
}

Lesson 4: Color Fade

// Source https://www.reddit.com/r/arduino/comments/9ry4mg/fading_rgb_leds_through_the_color_spectrum/

int red = 11; 
int green = 10;
int blue = 9;
int t = 10; // Time for delay

void setup(){
    pinMode(red, OUTPUT);
    pinMode(green, OUTPUT);
    pinMode(blue, OUTPUT);
}
void Fade(){
  for( int i = 0; i <= 255; i++){
    analogWrite(red, i); // fade up 
    analogWrite(green, 255 - i); // fade down
    analogWrite(blue, 0); // do nothing
    delay(t);
  }
  for( int i = 0; i <= 255; i++){
    analogWrite(red, 255 - i); // fade down
    analogWrite(green, 0); // do nothing
    analogWrite(blue, i); // fade up 
    delay(t);
  }
    for( int i = 0; i <= 255; i++){
    analogWrite(red, 0); // do nothing
    analogWrite(green, i); // fade up
    analogWrite(blue, 255 - i); // fade down 
    delay(t);
  }
} 
void loop(){
Fade();
}

5. Extensions

• Use loops to fade between colors
• Add a button to change LED patterns
• Build a mini light show

Reflection

• Which part of wiring the LEDs was most confusing?
• What would you try next with an RGB LED?
• How could this be applied in real-world projects?

Questions to Ask

• What’s the purpose of a resistor in your circuit?
• How could you make your circuit interactive?
• What happens if you remove the delay in your code?